1. Field of the Invention
The present invention relates to the field of semiconductor manufacturing and, more particularly to a semiconductor package with a stiffener ring between a heat spreader and a wiring board and a method for manufacturing such a package.
2. Description of the Related Arts
Recent trends in electronic development have been toward light weight, miniaturization, high speed, multi-functionalization, high quality, high reliability, and low production cost. In order to satisfy these pressing demands, a ball grid array (BGA) package was introduced. Compared to a conventional plastic package, the BGA package has advantages of reduced mounting area on a curcuit board and excellent electronic characteristics.
While conventional plastic packages employ a lead frame, the BGA package employs a wiring board. Since external terminals of the BGA package, such as solder balls, can be formed on the entire surface of the wiring board, a high mounting density on an associated circuit board can be achieved. A printed circuit board, a ceramic substrate or a printed circuit tape may be used as the wiring board. Although the electrical connection between the wiring board and the chip was achieved mainly by a wire-bonding method, this connection has been recently achieved by a flip-chip bonding method, thereby improving speed of integrated circuit chips requiring high power and high frequency.
FIGS. 1 and 2 illustrate a semiconductor package 100 having a flip-chip bonded semiconductor chip 10. As shown in FIGS. 1 and 2, the semiconductor chip 10 is flip-chip bonded to the upper surface of a wiring board 20 using electrode bumps 12 (shown in FIG. 2). The flip-chip bonding area between the semiconductor chip 10 and the wiring board 20 is filled with an epoxy resin 30 by an underfilling method. An adhesive 42 is coated on four corners of the upper surface of the wiring board 20. A stiffener ring 50 is attached to the upper surface of the wiring board 20 by the adhesive 42. The stiffener ring 50 has an opening 52 at the center, through which the flip chip bonded semiconductor chip 10 is exposed. An adhesive 44 is coated on four corners of the upper surface of the stiffener ring 50, and a thermal interface material (TIM) 60 is coated on the back surface of the semiconductor chip 10. Then, a heat spreader 70 is attached to the upper surface of the stiffener ring 50 and the back surface of the semiconductor chip 10 by the adhesive 44 and the TIM 60, respectively. Multiple external connection terminals 80 (shown in FIG. 2) such as solder balls are formed on the lower surface of the wiring board 20. The terminals 80 are electrically connected to the semiconductor chip 10 through the wiring board 20.
Herein, the stiffener ring 50, which is attached to the upper surface of the wiring board 20, serves to prevent the warpage of the wiring board 20 and to more firmly attach the heat spreader 70 to the back surface of the semiconductor chip 10. If the heat spreader is attached to the back surface of the semiconductor chip without the stiffener ring, the adhesion strength between the heat spreader and the TIM on the back surface of the semiconductor chip may not be sufficient, and thus the heat spreader may be detached from the back surface of the semiconductor chip. However, in order to interpose the stiffener ring 50 between the wiring board 20 and the heat spreader 70, it is necessary that the adhesives 42 and 44 are respectively coated by two separate steps, that is, a step of coating the adhesive 42 on the upper surface of the wiring board 20, thereby attaching the stiffener ring 50 to the wiring board 20 and a step of coating the adhesive 44 on the upper surface of the stiffener ring 50, thereby attaching the heat spreader 70 to the stiffener ring 50. Therefore, the conventional semiconductor package 100 has a drawback in that the manufacturing process is complicated.